Evidence Collection, Packaging, and Chain of Custody
Evidence Collection, Packaging, and Chain of Custody
This domain tests whether evidence is collected without alteration, packaged to prevent loss or cross-transfer, and documented so that its identity and integrity are provable in court.
Core rules
- Collect each item individually; never commingle evidence from different locations or suspects.
- Package biological evidence in paper, not plastic, and air-dry wet items before sealing. Plastic traps moisture and promotes mold and DNA degradation.
- Sharps go in rigid puncture-resistant containers; liquids go in leakproof primary and secondary containers.
- Seal with tamper-evident tape across the closure, sign and date across the seal, and label with item number, description, location, collector, and date/time.
- Chain of custody: every transfer records from whom, to whom, date/time, and purpose. Gaps create admissibility challenges.
Worked example
A bloodstained shirt. Air-dry it in a clean, secure room away from sunlight; do not fold a wet stain onto itself. Place it in a paper bag, seal across the flap, initial and date the seal, and record the item in the log. The reasoning: moisture supports bacterial growth and DNA degradation; paper allows vapor exchange. Plastic would be appropriate only after the item is thoroughly dry and is generally avoided for biological evidence.
Traps
- Plastic bags for wet blood or plants.
- Sealing multiple items in one bag.
- A seal without initials and date.
- Chain-of-custody entries without times.
- Packaging wet evidence before drying.